Periodic multilayers deposited by Distributed Electron Cyclotron Resonance (DECR) sputtering were studied with synchrotron radiation at the ESRF bending magnet beam line BM5. In situ reflectivity measurements at a photon energy of 20keV have been carried out on these samples during a specific heat treatment. A dedicated furnace has been developed to heat the multilayers under vacuum from room temperature up to 550°C. [Ru/B4C]70 and [W/B4C]40 samples with repetition periods of about 4nm were chosen. Simulations of reflectivity measurements were performed to understand the evolution of layer thicknesses and interface widths. Additional ex-situ reflectivity measurements were done at 8keV before and after the annealing experiments to investigate irreversible effects. We will discuss the heat impact on the layered structure and in which way multilayer optics could be thermally pre-treated before their installation on synchrotron beam lines.

Thin films of highly oriented pyrolytic graphite (HOPG) give the opportunity to realize crystal optics with arbitrary geometry by mounting it on a mould of any shape. A specific feature of a HOPG is its mosaicity accompanied by mosaic focusing and high integral reflectivity. These characteristics are of interest for compact x-ray diagnostic tools and spectrometers. Another interesting feature is, due to the mosaic spread of the HOPG crystals, that it is possible also with a beam of low divergence to record a spectrum in a broad energy range even within one laser shot. That means that the HOPG spectrometer can act as a polychromator. The latter feature is important if irreversible changes in samples should be investigated or, e.g., if in time-resolved pump-probe experiments a spectrum should be recorded before sample degradation takes place due to high pump intensities. Different design considerations for a compact HOPG-spectrometer based on experimental and theoretical studies will be presented. For applications in plasma diagnostics and XAFS (x-ray absorption fine structure) the attainable energy resolution plays a central role and has been intensively investigated. The results of our investigations demonstrate that HOPG can be used as powerful optics for x-ray diagnostics as well as for x-ray absorption and emission spectroscopy.

We present a review of a hybrid Lobster optic built up of a mixture of standard Lobster Eye geometry and parabolically bent mirrors. This design has better angular resolution in one direction while still having a wide field of view in the other. We have performed some computer simulations and comparisons with standard LE optic, hence we can discuss the advantages and/or disadvantages of such design as well as possible operating modes, especially in the case of X-ray all-sky monitor. Additionally, we are going to show first laboratory samples of parabolically bent mirrors for hybrid lobster array which were produced using several different technologies.

X-ray focusing techniques using Kirkpatrick and Baez mirrors are promising due to their capability of highly efficient and energy-tunable focusing. We have been developing a hard-X-ray focusing system using K-B mirrors for an X-ray microscope. Here, we report the development of a mirror manipulator and focusing tests using the manipulator. Mirror alignment tolerances were estimated using two types of simulators: a ray-trace simulator and a wave-optical simulator. On the basis of the simulation results, the mirror manipulator was developed achieving optimum K-B mirrors setup. The focal size was achieved to be 48 x 36nm2 (V x H) in FWHM at 1km long beamline of SPring-8. The obtained spatial resolution test results indicate that a scanning microscope with the focused beam can resolve the line-and-space patterns of 80nm line width in a high visibility of 60%.

X-ray spectrograph has long been used as a means of diagnosing conditions of laser-produced plasmas, as information concerning both the temperature and density can be extracted from the emitted radiation. For the measurement of X-ray lines in the energy range of 0.6-6 keV, A curved crystal X-ray spectrometer of reflection type elliptical geometry is required. In order to obtain both high resolution and collection efficiency the elliptical geometry is more advantageous than the flat configurations. Elliptical curved crystals spectrograph with a relatively wide spectral range are of particular use for deducing electron temperatures by measurement of the ratios of lines associated with different charge states. Curved crystals analyzer was designed and manufactured for use on an experiment to investigate the properties of laser produced plasmas. The spectrograph has 1350mm focal length and for these measurements, utilized PET, LIF, KAP and MICA crystal bent onto an elliptical substrate. This crystal analyzer covers the Bragg angel range from 30 to 67.5. The analyzer based on elliptically geometrical principle, which has self-focusing characteristics. The experiment was carried out on Shanghai Shengguang-II Facility and aimed to investigate the characteristics of a high density plasma. Experimental results using Curved crystal analyzer are described which show spectrum of Ti, Au laser-plasma. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal. Spectra showing the main resonance
line were recorded with X-ray CCD and with laser energies 150J laser wavelength 350nm. The calculated wavelength resolution is about 500-1000.

We have tested the operation and spectral coverage of two different types of EUV light sources for EUV characterization of astronomical mirror coatings, gratings, filters and detectors. Based on successes reported by another group investigating EUV-range K and L shell emission, we tested the feasibility of using Bremmstrahlung emission from a standard x-ray tube with the beryllium window removed. The second source is a Penning gas discharge source reported previously. The range of characterization and combinations of cathode and gas materials has been extended. Using the C/Ne and C/CO2 combinations provides nearly full coverage of the 200-600 Å spectral range with a high density of spectra lines. Use of carbon cathodes as opposed to the standard aluminum or magnesium cathodes allows one to operate the source for a long period of time before having to break vacuum and replace the disposable cathodes.

X-ray reflectivity (XRR) is an effective non-destructive characterization method that has recently gained interest in the semiconductor industry for routine quality control. XRR is capable of measuring thin film properties such as density, thickness and interfacial characteristics. In particular, this method is being studied to determine its usefulness in characterizing porous SiO2, one possible replacement for standard SiO2 as a low-k dielectric for device miniaturization. A necessary component to evaluating these porous materials is to understand the level of porosity as determined by the overall density of the material. The density information can be obtained from the critical angle observed in XRR data, hence the necessity of accurate measurements. In this work, the authors explore the limitations of XRR for determining the overall density of a layer using a simulation and fitting program, SimulReflec, designed for x-ray and neutron reflectivity studies. This fitting program is applied to both experimental and simulated data. Various versions of noise have been added to simulated data and then re-fit to determine the sensitivity of the technique.

An energy dispersive x-ray diffraction and fluorescence (EDXRD/XRF) system with no moving parts was developed to monitor in situ the initial stages of thin film growth. The EDXRD/XRF system utilized a low power 25 W microfocus x-ray source and collimating polycapillary optics manufactured by X-Ray Optical Systems (XOS). Metastable semiconductor thin film samples containing phase-separated inclusions of Sn were analyzed for simulation of early deposition stages. The time required to obtain sufficient diffraction data from these thin films was on the order of 60 seconds. Diffraction and fluorescence data were simultaneously obtained making it possible to simultaneously determine the crystal structure and composition of thin films while they are growing. This has the potential for revolutionizing how new materials are developed and commercialized, significantly cutting development and process control costs. An additional XRF system was developed that utilized a low power 20 W microfocus x-ray source and a focusing polycapillary optic. The Sn minimum detectable limit of this system (samples of interest were Ge1-xSnx) was on the order of nanograms using the Sn-Lα signal, which corresponds to picograms from a Sn-Kα signal. Such low levels are usually only possible with a rotating anode source 103 times more powerful than the low power sealed tube source used in this experiment. An 100nm thin Ge1-xSnx sample made by ion implantation was analyzed with this XRF system. In 300 s, a detectable signal was obtained, indicating the viability of this system for in situ, thin film, composition monitoring and characterization of the first several monolayers of thin film growth.

Polycapillary and doubly curved crystal (DCC) optics coupled with small spot x-ray sources in a special X-Beam package provide compact, high-sensitivity, low-power, highly stable subsystems that can be used for in situ analyzers. These analyzers provide remote, unattended use for environmental applications, bench-top or in-line instruments for industrial applications, and point-of-care clinical instruments for medical diagnosis or monitoring. Micro x-ray fluorescence (μXRF) and monochromatic micro x-ray fluorescence (MμXRF) can be used to measure trace element concentrations and distributions. Parallel-beam and convergent-beam x-ray diffraction (XRD) can be used for in situ phase composition, texture, strain, and crystal structure measurements.

In this work we have studied the generation of Extreme Ultraviolet (EUV) light by a novel Compact Electron Cyclotron Resonance Ion Source (CECRIS). The EUV emission diagnostics of the ECR plasma was accomplished by means of a 1.5 m Grazing Incidence Monochromator which was operated in a wavelength range of 4-90 nm under the condition of medium to high resolution to discriminate between spectra arising from different Xeq+ (q = 1-10) charge states. One of the major accomplishments of this study is assignment of numerous new optical transitions for Xenon in the 10-80 nm range under absolute conditions to create a database for further investigations. High resolution spectra were recorded confirming fair contributions from highly excited Xe10+ and Xe9+ ionic states. Major outcome of this work is that the Xe10+ ion emission with λ = 13.4 nm may occurs with such a simplified and compact ECR source. The EUV emission of this particular line is of great interest for lithography applications.

In order to generate high energy densities of 13.5 nm radiation, an EUV Schwarzschild mirror objective with a numerical aperture of 0.44 and a demagnification of 10 was developed and adapted to a compact laser-based EUV source. The spherical mirror substrates were coated with Mo/Si multilayers systems. With a single mirror reflectance of more than 65% the total transmittance of the Schwarzschild objective exceeds 40 % at 13.5 nm. From the properties of the EUV source (pulse energy 3 mJ at 13.5 nm, plasma diameter approx. 300 μm), energy densities of 73 mJ/cm2 at a pulse length of 6 ns can be estimated in the image plane of the objective. As a first application, the formation of color centers in lithium fluoride crystals by EUV radiation was investigated. F2, F3 and F3+ color centers could be identified by absorption spectroscopy. The formation dynamics was studied as a function of the EUV dose. By imaging of a pinhole positioned behind the plasma, an EUV spot of 5 μm diameter was generated, which accomplishes direct writing of color centers with μm resolution.

In the paper a newly developed compact and debris-free laser plasma soft X-ray source is presented. The source is based on the double-stream gas puff target approach. The targets are formed by pulsed injection of high-Z gas (xenon, krypton or argon) into a hollow stream of low-Z gas (helium or hydrogen) using the valve system composed of two electromagnetic valves and equipped with the double-nozzle setup. The outer stream of gas confines the inner stream improving the gas puff target characteristics (higher density of high-Z gas at longer distance from the nozzle output). It causes efficient absorption of laser energy in a plasma and strong soft X-ray production. Additionally, the use of the double-stream gas puff target approach makes possible to avoid degradation of the nozzle by the laser plasma. Spectral characteristics of soft X-ray emission from the source are presented. Applications in X-ray pulsed radiography, microprocessing of polymers by direct soft X-ray photo-etching, and EUV technologies are discussed.

A CO2 laser driven Xe jet plasma is presented as light source system for EUV lithography. A short-pulse TEA C02 master oscillator power amplifier system and a pre-pulse Nd:YAG laser were used for plasma generation. The dependence of EUV plasma parameters, e.g. conversion efficiency, plasma image and in-band and out-of-band spectra, on the delay time between the pre-pulse and the main pulse laser was investigated. A maximum conversion efficiency of 0.6 % was obtained at a delay time of about 200 ns. In addition, characteristics of fast ions were measured by the time-of-flight method. The peak energy of the fast ion energy distribution decreased significantly at delay times larger than 200 ns. This result is very promising with respect to collector mirror lifetime extension by magnetic field mitigation.

Laser produced plasma EUV source is the candidate for high quality, 115 W EUV light source for the next generation lithography. Cost effective laser driver is the key requirement for the realization of the concept as a viable scheme. A CO2 laser driven LPP system with a Xenon droplet target is therefore a promising light source alternative for EUV. We are developing a high power and high repetition rate CO2 laser system to achieve 10 W intermediate focus EUV power. High conversion efficiency (CE) from the laser energy to EUV in-band energy is the primarily important issue for the concept to be realized. Numerical simulation analysis of a Xenon plasma target shows that a short laser pulse less than 15 ns is necessary to obtain a high CE by a CO2 laser. This paper describes on the development of a CO2 laser system with a short pulse length less than 15 ns, an average power of a few kW, and a repetition rate of 100 kHz based on RF-excited, axial flow CO2 laser modules. Various issues are reported on the laser system design, namely l00W seeder, parasitic oscillation suppression, small signal gain and saturation fluence, and beam quality. Additional approach to increase the amplification efficiency is discussed.
Acknowledgement: This work was supported by NEDO.

We demonstrate single-shot measurement of the fringe visibility of 13-nm high-order harmonic beam in a Young's double slit experiment. The fringe visibility of 0.95 was obtained for 13-nm harmonics with optimal phase-matching condition. To our knowledge, this is the first demonstration of the fringe visibility measurement of the 13-nm harmonic beam with a single-shot. This result shows that the 13-nm harmonic beam is highly spatial-coherent light source and useful for applications in imaging and microscopy.

Hard x-ray spectra were recorded by the High Energy Electronic X-Ray (HENEX) spectrometer from a variety of targets irradiated by the Omega laser at the Laboratory for Laser Energetics. The HENEX spectrometer utilizes four reflection crystals covering the 1 keV to 20 keV energy range and one quartz(10-11) transmission crystal (Laue geometry) covering the 11 keV to 40 keV range. The time-integrated spectral images were recorded on five CMOS x-ray detectors. Spectra were recorded from gold and other metal targets and from krypton-filled gasbags and hohlraums. In the spectra from the krypton-filled targets, the helium-like K-shell transitions n=1-2, 1-3, and 1-4 appeared in the 13 keV to 17 keV energy range. A number of additional spectral features were observed at energies lower than the helium-like n=1-3 and n=1-4 transitions. Based on computational simulations of the spectra using the FLYCHW/FLYSPEC codes, which included opacity effects, these additional features are identified to be inner-shell transitions from the Li- like through N-like krypton charge states. The comparisons of the calculated and observed spectra indicate that these transitions are characteristic of the plasma conditions immediately after the laser pulse when the krypton density is 2x1018 cm-3 and the electron temperature is in the range 2.8 keV to 3.2 keV. These spectral features represent a new diagnostic for determining the charge state distribution, the density and electron temperature, and the plasma opacity. The intense 13 keV krypton K-shell emission should be useful for backlighters and radiography of dense plasmas. Laboratory experiments indicate that it is feasible to record K-shell spectra from gold and higher Z targets in the > 60 keV energy range using a Ge(220) transmission crystal.

We have measured the production of hν &ges; 10 keV x rays from low-density, Ge-doped aerogel targets at the OMEGA laser (Laboratory
for Laser Energetics, University of Rochester). The targets were 1.2mm long by 1.5mm diameter beryllium cylinders filled with Ge-doped (20 atomic percent) SiO2 aerogel. The doped-aerogel density was 4.8 or 6.5 mg/cc. These targets are a major advance over previous doped aerogels: instead of suspending the dopant in the SiO2 matrix, the Ge atoms, with chemistry similar to Si, are incorporated directly in the matrix. Forty beams of the OMEGA laser (λ = 351 nm) illuminated the two cylindrical faces of the target with a total power of approximately 18 TW. The laser interaction strongly ionizes the target (ne/ncr&les; 0.1-0.2), and allows the laser-bleaching wave to ionize supersonically the high-Z emitter ions in the sample. Ge K-shell x-ray emission was spectrally resolved with a two-channel crystal spectrometer and recorded with temporal resolution with a set of calibrated photoconductive devices (PCDs). The heating of the target was imaged with a gated (60 ps time resolution) x-ray framing camera, filtered to observe > 4 keV. 2-D radiative-hydrodynamic calculations predict rapid and uniform heating over the whole target volume with minimal energy losses into hydrodynamic motion. The calculations predict 150-200 J of x-ray energy output with hν &ges; 10 keV.
Good agreement between measurements and the calculations is found.

A compact, tabletop terawatt forsterite laser (1.24 μm /100 mJ/ 80 fs) is used for generation of fast hard x-ray radiation from laser-produced plasmas. Plasmas are created on massive solid Fe and Cu targets. X-ray radiation is studied using a focusing crystal von Hamos spectrometer with a CCD linear array as x-ray detector. High efficiency of the spectrometer in a wide spectral range allows us to record x-ray spectra by one laser shot. Intense Kα radiation is studied with high spectral resolution (λ/δλ~1000) at various focusing conditions: main laser radiation and second harmonic radiation. With a copper target the Kα radiation yield was equal to 4×109 photon/pulse in 4π steradian, that corresponds to conversion efficiency of 0.02%. Processes responsible for ultrafast hard x-ray radiation are discussed.

Experiments in laser physics often require more comprehensive information about a beam than can be extracted from temporal and spatial profile measurement alone. In particular, the wavefront has considerable effect on both irradiance and phase distribution near focus, and thus large impact on the efficiency of non-linear coherent processes such as generation of higher harmonics from femtosecond ultra-short laser pulses. Here we present Hartmann-Shack wavefront measurements of ultra-broadband laser pulses with a spectral bandwidth of >190 THz, which are produced by focusing amplified pulses from a 20 fs Ti:Sapphire oscillator-amplifier system into an Argon filled hollow fibre of 400 μm diameter. After re-compression the pulses were analyzed with the Hartmann-Shack sensor, both at a distance of 140 cm behind the fibre exit and after reflection from a concave mirror (f = 100 mm). Measurements of the overall polychromatic wavefront are faced to a couple of quasi-monochromatic ones covering the whole spectrum. Incoherent superposition of the spectral components yields excellent agreement to the measured overall wavefront, showing that the total wavefront can be sensed reliably by a single measurement. Furthermore, comparison of numerically propagated and measured wavefronts shows good agreement for different spectral components: the measured overall wavefront fits, within sensor accuracy, the numerically propagated one obtained by incoherent superposition of its quasi-monochromatic parts. Drawbacks and opportunities of the Hartmann-Shack technique in ultra-short pulse sensing are briefly discussed.

Absolute x-ray calibration of laser-produced plasmas was performed using a focusing crystal von Hamos spectrometer. The plasmas were created by an Nd-YAG laser (0.53 μm/200 mJ/3 ns/10 Hz) on massive solid targets (Mg, Cu, Zn, Sn, Mo, Ta, Ti, Steel). Cylindrical mica crystal (radius of curvature R=20 mm) and a CCD linear array detector (Toshiba model TCD 1304AP) were used in the spectrometer. Both the mica crystal and CCD linear array were absolutely calibrated in the spectral range of λ=7-15 Å. The spectrometer was used for absolute spectral measurements and the determination of the plasma parameters. The unique target design allowed for multiple instruments to observe the plasma simultaneously which improved analysis. High spectrometer efficiency allows for the monitoring of absolute x-ray spectra, x-ray yield and plasma parameters in each laser shot. This spectrometer is promising for absolute spectral measurements and for monitoring laser-plasma sources intended for proximity print lithography.

We used the Monte Carlo code EGSnrc to simulate electron energy loss profiles as well as angle resolved x-ray spectra for metal-layer/substrate combinations in the primary electron energy range of 60-160 keV. We were furthermore able to separate the bremsstrahlung fraction originating in the substrate from that of the metal layer. The simulations were accompanied by experimental investigations. High-energetic electrons of 60-160 keV were directed onto 1-2 μm thin tungsten layers on top of 500 μm diamond substrates. The spectra were recorded by an energy resolved detector positioned in backward direction. We compared the experimental data with the simulation results and found good agreement. An enhanced monochromaticity in backward direction however, as expected from thin film theory, has not been observed due to the influence of the substrate.

We report on our progress towards the experimental realization of a liquid-metal-jet-anode x-ray source with high brightness. We have previously shown that this electron-impact source has potential for very high x-ray brightness by combining small-spot high-flux operation of the electron beam with high-speed operation of the regenerative liquid-metal-jet anode. In the present paper we review the system and describe theoretical calculations for improving the 50 kV, 600 W electron-beam focussing to ~30 μm spot size. With such a system the power density on the liquid-metal-jet would be ~400 kW/mm2, i.e., more than an order of magnitude higher than the power density on a state-of-the-art rotating anode.

Laser-Compton scattering is a promising method for generating high-brightness, ultrashort, energy-tunable X-rays. We have developed a compact X-ray source using laser-Compton scattering. Hard X-rays, ranging from 15 keV to 34 keV, were generated with a low-emittance, 38 MeV, 0.8 nC electron accelerator and a femtosecond 4TW Ti:sapphire laser. The created X-rays were composed of 2×106 (5×105) photons/pulse for interaction angles between an electron bunch and a laser pulse of 165° (90°). A highly accurate timing synchronization scheme was employed, and the fluctuation of the generated X-rays was suppressed to 11% (rms) for the 90° scattering. The spatial (angular) distributions for the intensity and the energy of the generated X-ray were measured, and agreed well with theoretical calculations. Thus, X-ray imaging has been demonstrated using a phase-contrast technique with the interference of an X-ray beam.

Results of the development and study of a table-top z-pinch and laser-plasma x-ray/EUV facility "Sparky" are presented. The goal of development of this facility was to obtain high density and temperature plasmas of high atomic number elements in two different ways: vacuum spark or thin (micron-scale) wires in z-pinch device, and laser-plasma source with a flat target.

Energy and angular distributions of the fast outgoing electron beam induced by the interaction of 1-2 J, 30 fs, 3-20x1018 W/cm2 laser with a thin foil or a gas jet target are characterized by using both an electron spectrometer and Bremsstrahlung induced photo-nuclear reactions. The supra-thermic electron beams production was investigated for a solid target versus its thickness and its Z number, and for a gas jet target versus its pressure. Using a polyethylene target and a supersonic Helium gas jet target, we measured, respectively, up to 4x108 and 3x109 electrons produced per laser pulse, with energies up to, respectively, 60 MeV and 160 MeV. The associated Boltzmann temperature of these electrons is colder for thin foils (9 MeV) than for gas jet (18 MeV). About, respectively 0.06% and 1% of the laser energy has been converted to outgoing electrons with energies above 5 MeV. Such electrons leave the plasma in the laser direction within a cone with an opening angle of, respectively, 2.5° and 8.5°. We discuss the physical processes of electron acceleration. Numerical calculations show a good agreement with the experiments.

A diffraction plane grating with single-layer coating able to reach photon energy up to 3 keV (possibly 4 keV) will be adopted at the TwinMic beamline at ELETTRA. The TwinMic beamline will exploit the unique capabilities of the novel twin X-ray microscope, which combines scanning and full-field imaging microscopes in a single multipurpose end-station. The needed moderate energy resolving power will be provided by a variable included angle plane grating monochromator working in a collimated light mode (also known as collimated SX700). This configuration allows freely selection of the incidence and diffraction angles at the grating, therefore permitting, for instance, to optimize its efficiency. This monochromator uses two mechanically ruled gratings to cover a very wide working energy range. The first grating goes from 150 eV to 1000 eV while the second goes from 600 eV to 4 keV. The two gratings were ruled using the CARL ZEISS Grating Ruling Engine GTM6, which is operated under interferometric control. The high-energy plane grating, with a line density of 600 lines/mm, has a triangular profile with a blaze angle of 0.4° and an apex angle of 178°. The grating profile is ruled on a silicon substrate and is covered with a 30 nm thick gold film. The small blaze angle permits one to work in blaze condition at very grazing incidence angles and therefore allows reaching high photon energies not accessible by means of conventional gratings.

A microfocus x-ray tube is useful in order to perform magnification digital radiography including phase-contrast effect. The 100-μm-focus x-ray generator consists of a main controller for regulating the tube voltage and current and a tube unit with a high-voltage circuit and a fixed anode x-ray tube. The maximum tube voltage, current, and electric power were 105 kV, 0.5 mA, and 50 W, respectively. Using a 3-mm-thick aluminum filter, the x-ray intensity was 26.0 μGy/s at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.50 mA. Because the peak photon energy was approximately 38 keV using the filter with a tube voltage of 60 kV, the bremsstrahlung x-rays were absorbed effectively by iodine-based contrast media with an iodine K-edge of 33.2 keV. Magnification angiography including phase-contrast effect was performed by three-time magnification imaging with a computed radiography system using iodine-based microspheres 15 μm in diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 μm with high contrasts.

We present a system for diagnostic imaging of x-ray sources using a compound refractive lens. Such a system can be built at a low cost, yet image at resolutions of 2 μm or better. The essential components of the system are the source to be imaged, a compound refractive lens and imaging detector (either electronic or film). In addition, spatial and spectral filters can be added to improve resolution and a laser alignment system can be used to rapidly align the source, lens and camera.

We investigated performance of ultrafast laser-based x-ray source for phase contrast imaging in 2D projection imaging and in enhanced micro-CT imaging. Good quality images were obtained, including images of small animals, in the single energy and multiple energy, in line phase-contrast enhancing geometry using x-ray line energy matching object thickness and density. Phase information has been inferred from images obtained at the same x-ray energy but at different object-to-detector distances and also from images obtained at the same object-to-detector distance but with different K-alpha line energies. Ultrafast laser-based, compact, x-ray source is a promising technique for micro-CT systems. Its utilization might result in faster scans with lower radiation dose, better spatial and contrast resolution and also femtosecond temporal resolution. In addition, it might allow practical implementation of dual-energy and phase-contrast imaging micro-CT that is not possible with conventional micro-CT.

The qualities of initial reconstructed images suffer from reduced resolution due to all kinds of factors which are relative to the cone-beam CT imaging system. The blurring is one of the most difficult problems caused by imaging system. To suppress the blurring in the reconstructed image, some research has been conducted on the deconvolution using a point spread function (PSF), but Modulation Transfer Function (MTF) is used here instead of PSF. The MTF can be obtained by application of the two-dimensional (2-D) Fourier transform to the point-spread function (PSF). In this paper, the impact of various factors on MTF is subsequently illustrated with computer simulations. We use numerical phantom to calculate the MTF, and analyze its variation with position. The size of X-ray focus and magnification are also two important factors which influence MTF, so their effects on MTF are simulated. In addition, different longitudinal positions also influence the MTF. Finally, we use 3D Feldkamp and Radon transform algorithm to reconstruct the images respectively. By comparing the results obtained from the two representative reconstruction algorithms, the characterization of MTF of the cone-beam CT algorithm can be evaluated.

Traditional computed tomography reconstructions are limited by many kinds of artifacts. In general, they give dissatisfactory image. To reduce image noise and artifacts, we propose an iterative approach processing these reconstructed images, which are acquired by analytical inversion methods. In this paper, we describe ordered subsets expectation maximization (OS-EM) algorithms. Our reconstruction algorithm is based on a maximum a posteriori (MAP) approach, which allows us to incorporate priori information to stabilize the EM algorithm. The OS-EM algorithm provides good quality reconstructions after only a few iterations, yet beyond a critical number of iterations, the artifact is magnified due to inherent instability problem of OS-EM. To overcome this problem, we estimate the number of iterations by using priori information, the priori information is the blank region in the projection data resulting from a part of X-ray's air scan. In ideal case these corresponding regions in reconstructed image should also be blank. But in practice, they are not blank any more due to containing noise and artifacts. Based on this prior information, we can obtain an optimum number of iterations in the small air scan region. We process the whole estimated image with the same number of iterations. The two processes are carried on at the same time. Then the resulting image is considered as the best restoration of the original image. Experiments show that by our method, the artifacts and noise can be greatly suppressed and the contrast can be significantly improved.

Two samples of the new type of X-ray spectral elements--sliced multilayer grating (SMG) for 4.4-5 nm interval based on Co/C multilayer coatings have been produced and tested. A novel experimental approach based on a flow proportional counter was introduced and used to measure diffraction efficiency of SMG gratings. Spectra of Al discharge plasma were obtained with one of the SMGs. The properties of the SMG gratings are discussed.

In the processing diagnosis of the inertia confinement fusion (ICF), the ring coded aperture imaging technique is applied in order to gain high space and time resolutions simultaneously. The key of acquiring high spatial resolution is how to obtain a point spread function of an imaging system. The common method is the firsthand projection method which is an approximate one. The x-ray diffraction effect is neglected in the method, so the resolution of reconstructed image is decreased. We have derived the point spread function (PSF) of the ring coded aperture from scalar diffraction theory. And the Wiener filter is fabricated on the basis of the PSF. In National Key Laboratory of Laser Fusion, at China Academy of Engineering Physics, the imaging experiment on the diagnosis of ICF is completed using the ring coded aperture plate with inner diameter d1 = 250μm and outer diameter d2 = 260μm .The obtained coded image is processed by the Wiener filter which diffractive effect is considered. The processed results have shown that resolution and modulation contrast of acquired image are evidently better than the results obtained by the firsthand projection method.

This generator consists of the following components: a constant high-voltage power supply, a filament power supply, a turbomolecular pump, and an x-ray tube. The x-ray tube is a demountable diode which is connected to the turbomolecular pump and consists of the following major devices: a molybdenum rod target, a tungsten hairpin cathode (filament), a focusing (Wehnelt) electrode, a polyethylene terephthalate x-ray window 0.25 mm in thickness, and a stainless-steel tube body. In the x-ray tube, the positive high voltage is applied to the anode (target) electrode, and the cathode is connected to the tube body (ground potential). In this experiment, the tube voltage applied was from 22 to 36 kV, and the tube current was regulated to within 100 μA by the filament temperature. The exposure time is controlled in order to obtain optimum x-ray intensity. The electron beams from the cathode are converged to the target by the focusing electrode, and clean Kα rays are produced through the focusing electrode using a 20-μm-thick zirconium filter. The x-ray intensity was 12.1 μGy/s at 1.0 m from the x-ray source with a tube voltage of 30 kV and a tube current of 100 μA, and monochromatic radiography was performed using a computed radiography system.

This paper presents a method of a nano-positioning control for the high precision focusing of a doubled ellipsoidal condenser reflective mirror using 5-axis manipulator. We have developed the compact vertical type of soft X-ray microscopy system with 50nm resolution for biomedical application. This microscopy system is composed of a laser plasma x-ray source, doubled ellipsoidal condenser reflective optics, diffractive zone plate optics and MCP coupled with CCD to record an x-ray image. The X-ray source was focused on a sample by a doubled ellipsoidal condenser reflective mirror. X-ray source focusing will increase the photon density in the object plane and is very important to approach high resolution imaging. Required degree of freedom (DOF) of optics aligner in X-ray microscope is dependent on the kind of optics, but generally 5-DOF is needed. We used 5-axis manipulator that consists of three linear motions (X, Y and Z) and two tilting motions (θx, θy). A linear translation stage is adopted a kind of DC motor with a linear resolution 50nm and travel range of 5mm. The mechanism was controlled with PID controller augmented with closed feedback loop for precision control. A two axis tilt stage is employed a design resolution of 0.23μrad and tilt range of ±7deg. We have designed 5-axis manipulator for the precision position control of condenser mirror optics and have developed to control algorithm by inverse kinematics. The performance of the proposed 5-DOF manipulator is evaluated by using a laser interferometer system with two plane mirror reflectors. The experimental results are depicted in this paper.

A compact soft X-ray microscope system has been developed for biological applications with nano-scale resolution. Soft X-ray used to the system is emitted from a solid target by using Nd-YAG pulsed laser. Boron nitride (BN) is used as the target materials in the system. The optics of the microscope system is adopted with wolter type-I mirrors, which is consisted of a condenser mirror with demagnification of 1/4× and an object mirror with magnification of 32×. The surface roughness of the machined wolter mirrors is about 0.8 nm (Ra) after polishing. In this paper, the X-ray characteristics, i.e., spectrum and intensity emitted from laser plasma-based x-ray source was measured. Imaging test using the system was performed with gold 2000 mesh. The spatial resolution of the soft x-ray microscope system was obtained about 900 nm.

We demonstrate compact transmission soft X-ray microscope system with 50 nm spatial resolution for the life and physical science. This x-ray microscope operates at photon energy from 284 eV to 543 eV, so called 'water window' region (2.3~4.4nm), where natural contrast between carbon (protein) and oxygen(water) allows imaging of unstained biological material in their natural, hydrated environment. The compact transmission soft x-ray microscope is based on a laser plasma x-ray source, tandem ellipsoidal condenser reflective optics, diffractive zone plate optics and x-ray sensitive charge-coupled device (CCD) to record an x-ray image. The source is a liquid-jet target laser plasma source, which is practically debris free and suitable for high average power operation. The flux, brightness and bandwidth of this source has been simulated and optimized for X-ray microscopy for biology application. A tandem ellipsoidal reflective mirror operates as condenser and illuminates the sample. The high resolution imaging is currently performed with a ~12% efficient nickel zone plate with an outmost zone width of 35nm. In conclusion, we suggested a possibility of the compact soft x-ray microscopy system with 50 nm spatial resolution as a suitable tool for the wide range of studies such as biological imaging, environmental samples, and nanostructure analysis.

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Journal of Applied Remote SensingJournal of Astronomical Telescopes Instruments and SystemsJournal of Biomedical OpticsJournal of Electronic ImagingJournal of Medical ImagingJournal of Micro/Nanolithography, MEMS, and MOEMSJournal of NanophotonicsJournal of Photonics for EnergyNeurophotonicsOptical EngineeringSPIE Reviews